Biomedical subjects

M B Talawar

Publications and source records attributed to M B Talawar.

21 records · Page 2Linked to original sources

PubMed2004

Studies on lead-free initiators: synthesis, characterization and performance evaluation of transition metal complexes of carbohydrazide.

Cobalt, nickel and zinc tris(carbohydrazide) perchlorates (CoCP, NiCP and ZnCP) as well as copper bis(carbohydrazide) perchlorate (CuCP) of desired morphology and bulk density (0.85-0.95 g/cm3) have been synthesized during this work. The synthesis was carried out by addition of the aqueous solution of cobalt/nickel/copper/zinc perchlorates to the aqueous solution of carbohydrazide. The products were characterized by the metal content analysis and FTIR. The IR spectra and ESCA brought out the coordination of both the end amino groups of carbohydrazide with the central metal ion. Differential thermal analysis (DTA) curve indicated that CoCP, NiCP and ZnCP are thermally stable in the temperature range of 220-285 degrees C, unlike CuCP (120 degrees C). The activation energy determined by TG measurements was found to be 140-180 kJ/mol for CoCP, NiCP and ZnCP. Sensitivity data revealed their sensitivity to friction stimuli (1 kg). Impact sensitivity test results corresponded to h50% of 50-60 cm with the exception of CuCP (h50%, 11 cm). In order to assess the performance as detonants, the selected compounds were detonated on a lead witness plate of 3 mm thickness using fuse wire as well as evaluated in conjunction with tetryl in detonator No. 27 tube. The results obtained in terms of extent of damage to witness plate were on par with the standard detonator No. 27 containing azide, styphynate and aluminium metal (ASA) composition.

Cobalt↗

PubMed2004

Computer simulation for prediction of performance and thermodynamic parameters of high energy materials.

A new code viz., Linear Output Thermodynamic User-friendly Software for Energetic Systems (LOTUSES) developed during this work predicts the theoretical performance parameters such as density, detonation factor, velocity of detonation, detonation pressure and thermodynamic properties such as heat of detonation, heat of explosion, volume of explosion gaseous products. The same code also assists in the prediction of possible explosive decomposition products after explosion and power index. The developed code has been validated by calculating the parameters of standard explosives such as TNT, PETN, RDX, and HMX. Theoretically predicated parameters are accurate to the order of +/-5% deviation. To the best of our knowledge, no such code is reported in literature which can predict a wide range of characteristics of known/unknown explosives with minimum input parameters. The code can be used to obtain thermochemical and performance parameters of high energy materials (HEMs) with reasonable accuracy. The code has been developed in Visual Basic having enhanced windows environment, and thereby advantages over the conventional codes, written in Fortran. The theoretically predicted HEMs performance can be directly printed as well as stored in text (.txt) or HTML (.htm) or Microsoft Word (.doc) or Adobe Acrobat (.pdf) format in the hard disk. The output can also be copied into the Random Access Memory as clipboard text which can be imported/pasted in other software as in the case of other codes.

Chemistry, Physical↗

PubMed2003

Synthesis, characterization and thermal studies of (Ni/Co) metal salts of hydrazine: potential initiatory compounds.

Nickel hydrazinium nitrate (NiHN) and cobalt hydrazinium nitrate (CoHN) were prepared by reacting their respective metal nitrates with hydrazine hydrate at 25 and 65 degrees C. The compounds were characterized by metal content and infrared (IR) spectroscopy. Differential thermal analysis (DTA) results suggest that the nickel complex is relatively more stable than the cobalt complex. The activation energy determined by DTA and ignition delay measurements corresponds to an energy of activation (E(a)) of 80+/-4 kJ/mol for NiHN and that of 150+/-8 kJ/mol for CoHN. Thermo gravimetry (TG) also revealed more rapid decomposition of NiHN than that of CoHN in the temperature region of 215-235 degrees C. High temperature Fourier transform-infrared (FT-IR) studies indicated rupture of the Ni-Co-N bond as the primary step in the thermolysis. As regards sensitivity to mechanical stimuli, NiHN was found to be less impact sensitive while CoHN exhibited less friction sensitivity. The study revealed that NiHN could be used alone as well as in combination with oxidizer/fuel as initiators depending upon the specific requirements. The effect of silver azide and glass on the sensitization of NiHN was also studied. CoHN appears to be an effective ballistic modifier in enhancing burning rates of composite propellants.

Carcinogens↗